Dual-fuel engine

A dual-fuel engine runs on a gaseous or low-flashpoint fuel with a liquid pilot fuel for ignition, switching to full liquid operation when the alternative fuel is unavailable. Low-pressure Otto-cycle designs (such as WinGD X-DF and Wartsila DF) are simpler but slip more methane; high-pressure diesel-cycle designs (MAN ME-GI) slip far less at higher cost. The architecture now extends to methanol and ammonia, giving owners a hedge against fuel availability and price while meeting EEXI and CII through lower-carbon fuel when supplied.